21893820 has 48 divisors (see below), whose sum is σ = 66020640. Its totient is φ = 5389056.

The previous prime is 21893813. The next prime is 21893827. The reversal of 21893820 is 2839812.

It is an interprime number because it is at equal distance from previous prime (21893813) and next prime (21893827).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21893827) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13255 + ... + 14814.

It is an arithmetic number, because the mean of its divisors is an integer number (1375430).

Almost surely, 2^21893820 is an apocalyptic number.

21893820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21893820 is an abundant number, since it is smaller than the sum of its proper divisors (44126820).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21893820 is a wasteful number, since it uses less digits than its factorization.

21893820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28094 (or 28092 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 21893820 is about 4679.0832435425. The cubic root of 21893820 is about 279.7524172002.

The spelling of 21893820 in words is "twenty-one million, eight hundred ninety-three thousand, eight hundred twenty".